package chixing.day11.work;

public class StringDemo {
    public static void main(String[] args) {
        //cahr[] :{'h','e','l','l','0','',....''}
        StringBuilder builder = new StringBuilder("hello");
        //修改的是原来的字符数组(可能还会扩容)
        builder.append("cat");

        String str = "abfsgkfrsg";
        str.replace('a','A');
        str.replaceAll("a","A");

        String s;//声明变量
        //System.out.println(s);变量s还未初始化所以不能输出
    }
}
